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Subject: Re: [PATCH v2 6/7] misc: bcm-vk: add Broadcom VK driver
To:     Randy Dunlap <rdunlap@infradead.org>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        David Brown <david.brown@linaro.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Shuah Khan <shuah@kernel.org>, bjorn.andersson@linaro.org,
        Shuah Khan <skhan@linuxfoundation.org>,
        Arnd Bergmann <arnd@arndb.de>
Cc:     "Rafael J . Wysocki" <rafael@kernel.org>,
        linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-fsdevel@vger.kernel.org,
        BCM Kernel Feedback <bcm-kernel-feedback-list@broadcom.com>,
        Olof Johansson <olof@lixom.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Colin Ian King <colin.king@canonical.com>,
        Kees Cook <keescook@chromium.org>,
        Takashi Iwai <tiwai@suse.de>, linux-kselftest@vger.kernel.org,
        Andy Gross <agross@kernel.org>,
        Desmond Yan <desmond.yan@broadcom.com>,
        James Hu <james.hu@broadcom.com>
References: <20200220004825.23372-1-scott.branden@broadcom.com>
 <20200220004825.23372-7-scott.branden@broadcom.com>
 <827a4520-95ce-5264-90d9-ed730e5918e6@infradead.org>
From:   Scott Branden <scott.branden@broadcom.com>
Message-ID: <22c48aaf-21e2-56ab-3f40-e497a69cd936@broadcom.com>
Date:   Thu, 20 Feb 2020 16:06:44 -0800
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Hi Randy,

On 2020-02-19 5:04 p.m., Randy Dunlap wrote:
> Hi,
>
> On 2/19/20 4:48 PM, Scott Branden wrote:
>> diff --git a/drivers/misc/bcm-vk/Kconfig b/drivers/misc/bcm-vk/Kconfig
>> new file mode 100644
>> index 000000000000..c75dfb89a38d
>> --- /dev/null
>> +++ b/drivers/misc/bcm-vk/Kconfig
>> @@ -0,0 +1,42 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +#
>> +# Broadcom VK device
>> +#
>> +config BCM_VK
>> +	tristate "Support for Broadcom VK Accelerators"
>> +	depends on PCI_MSI
>> +	default m
> Need to justify default m. Normally we don't add drivers as enabled unless
> they are required for basic (boot) operation.
Will remove default m as not needed to boot.  Interesting other offload 
engines misc/ocxl/Kconfig and misc/cxl/Kconfig have default m.
>
>> +	help
>> +	  Select this option to enable support for Broadcom
>> +	  VK Accelerators.  VK is used for performing
>> +	  specific video offload processing.  This driver enables
>> +	  userspace programs to access these accelerators via /dev/bcm-vk.N
>> +	  devices.
>> +
>> +	  If unsure, say N.
>> +
>> +if BCM_VK
>> +
>> +config BCM_VK_H2VK_VERIFY_AND_RETRY
>> +	bool "Host To VK Verifiy Data and Retry"
> 	                 Verify
>
>> +	help
>> +	  Turn on to verify the data passed down to VK is good,
>> +	  and if not, do a retry until it succeeds.
> No timeout on that retry?
This is only enabled for debug purposes or fpga workarounds - no need 
for a timeout.
>
>> +	  This is a debug/workaround on FPGA PCIe timing issues
>> +	  but may be found useful for debugging other PCIe hardware issues.
>> +	  Small performance loss by enabling this debug config.
>> +	  For properly operating PCIe hardware no need to enable this.
>> +
>> +	  If unsure, say N.
>> +
>> +config BCM_VK_QSTATS
>> +	bool "VK Queue Statistics"
>> +	help
>> +	  Turn on to enable Queue Statistics.
>> +	  These are useful for debugging purposes.
>> +	  Some performance loss by enabling this debug config.
>> +	  For properly operating PCIe hardware no need to enable this.
>> +
>> +	  If unsure, say N.
>> +
>> +endif
> cheers.